Homogenization is the breaking down and mixing of the components of an emulsion or dispersion. A major use of homogenizers is to break down and disperse milk fat into the bulk of skim milk. This delays creaming of milk fat globules. Homogenizers are also used to process other emulsions such as silicon oil and to process dispersions such as pigments, antacids and various paper coatings.
In the most widely used type of homogenizer, the emulsion is introduced at high pressure of from 500 psi to 10,000 psi to a central bore within an annular valve seat. The emulsion is forced out through a narrow gap between the valve seat and a valve plate. Through the gap, the emulsion undergoes extremely rapid acceleration as well as an extreme drop in pressure. This violent action through the valve breaks down globules within the emulsion to produce the homogenized product.
The degree of homogenization is a function of the difference between the pressure of the emulsion at the inlet of the valve and the pressure at the outlet. In the past, homogenizers have not typically been required to operate at inlet pressures of greater than 10,000 psi. However, recent applications such as cell disruption have required significantly higher inlet pressures of about 15,000 psi or more.
One available homogenizer system includes a homogenizer valve mounted to the side of a pump block. The pump is a plunger pump in which three plungers operate in parallel at 120.degree. phase shifts relative to each other. The three plungers draw from a common suction manifold and discharge into a common discharge manifold which delivers the high pressure fluid to the homogenizer valve. The suction and discharge manifolds are cross bores which extend parallel to opposite faces of the block. Three valve bores drilled through one of those faces join the two manifolds, and a one-way valve assembly is positioned at each end of each of those valve bores. Another set of three bores is drilled through an adjacent face of the block to form pump chambers. Each pump chamber intersects each valve bore at a 90.degree. angle. Each plunger reciprocates in a pump chamber to draw fluid through a suction valve from the suction manifold and discharge that fluid at higher pressure through a discharge valve into the discharge manifold.